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AbstractBackground??Retinitis pigmentosa belongs to a large group of degenerative diseases of the retina with a hereditary background. It involves loss of retinal photoreceptor cells and consequently peripheral vision. At present there are no satisfactory therapeutic options for this disease. Just recently the use of mesenchymal stem cells has been discussed as one therapeutical option for retinal degeneration, as they have been shown to differentiate into various cell types, including photoreceptor cells. In this article we wanted to investigate the potency of mesenchymal stem cells to induce rescue effects in an animal model for retinitis pigmentosa, the rhodopsin knockout mouse.Methods??For the experiments, three experimental groups of 10 animals each were formed. The first group consisted of untreated rhodopsin knockout (rho-/-) animals used as controls. The second group consisted of rho-/-mice that had received an injection of mouse mesenchymal stem cells, which were transduced using an adenoviral vector containing the sequence for the green fluorescent protein (GFP) prior to transplantation. In the third sham group, animals received an injection of medium only. Thirty-five days after transplantation, GFP-expressing cells were detected in whole-mount preparations of the retinas as well as in cryostat sections. For the detection of rescue effects, semi-thin sections of eyes derived from all experimental groups were produced. Furthermore, rescue effects were also analysed ultrastructurally in ultrathin sections.Results??Histological analysis revealed that after transplantation, cells morphologically integrated not only into the retinal pigment epithelium but also into layers of the neuroretina displaying neuronal and glial morphologies. Furthermore, significant rescue effects, as demonstrated by the occurrence of preserved photoreceptor cells, were detected.Conclusions??Our data indicate that mesenchymal stem cells can prolong photoreceptor survival in the rhodopsin knockout mouse, also providing evidence of a therapeutical benefit in retinitis pigmentosa. [ABSTRACT FROM AUTHOR]

Purpose: To determine the potential of adenovirally transduced bone marrow stromal cells (BMSCs) to differentiate into retinal pigment epithelial-like cells and to evaluabe possible rescue effects after transplantation into the retinas of Royal College of Surgeons (RCS) rats., Methods: Through a high-capacity adenoviral vector expressing either green fluorescent protein (GFP) or pigment epithelial-derived factor (PEDF), rat MSCs were transduced in vitro before subretinal transplantation into Wistar rats or, alternatively, RCS rats. Two months after cell injection, the rats were killed and the eyes enucleated. The eyes were then investigated light microscopically or processed for electron microscopic investigations. Cell differentiation and integration were analyzed immunocytochemically using antibodies against cytokeratin and the tight junction protein ZO-1. Electroretinography was performed 16 days after injection of cells, to check whether a functional rescue could be detected., Results: In vitro experiments in cocultured human MSCs and human RPE cells showed that MSCs adopted RPE-like characteristics. In grafting experiments, some rat MSCs integrate into the host RPE cell layer of Wistar and RCS rats, indicated by their hexagonal morphology. Subretinally transplanted cells express the epithelial marker cytokeratin and establish tight junctions with the host RPE cells. Furthermore, rescue effects can be demonstrated after grafting of vector-transduced and nontransduced MSCs in semithin sections of dystrophic retinas. Ultrastructurally, MSCs can be detected on top of host RPE and in close contact with photoreceptor outer segments phagocytosing rod outer segments., Conclusions: Taken together, these results raise the possibility that MSCs have the potency to replace diseased RPE cells and deliver therapeutic proteins into the subretinal space to protect photoreceptor cells from degeneration.

Because the neural differentiation capacity of bone marrow stromal cells (BMSCs) is still a matter of controversial debate, we performed a thorough investigation into the differentiation capacity of human BMSCs and examined their therapeutic potency. BMSCs were isolated from the femur and kept in cell cultures with various cultivation protocols being applied. In standard culture conditions using a fetal calf serum-enriched medium, while not exhibiting a neural phenotype, the majority of cells expressed a variety of neuronal marker proteins as well as the astrocyte marker GFAP. Only a minority of stem cells expressed nestin, a marker for neural precursor cells. Cultivation in serum-free medium supplemented with specific growth factors resulted in a markedly higher percentage of nestin-positive cells. To establish the therapeutic potency of bone marrow-derived cells, the synthesis of neurotrophic factors such as NGF, BDNF and GDNF was analyzed under non-stimulating standard culture conditions as well as after a neural selection procedure. The therapeutic potency of BMSCs was further examined with regard to their migratory potential in vitro and after transplantation in vivo. After stereotactic engraftment into the lateral ventricle of adult rats, mesenchymal stem cells were seen to adhere to the ependymocytes and cells of the choroids plexus. Afterwards grafted cells passed through the ependymal barrier, locating in the subventricular space. Their BMSCs took up a close host graft interaction without any degenerative influence on the host cells. Furthermore, there was morphological as well as immunohistochemical evidence for a transdifferentiation within the host tissue. In addition, BMSCs could be efficiently transduced using a third-generation adenoviral vector, indicating their potential feasibility for a gene-therapeutic option.

Gene expression profiling was performed to identify genes involved in the development of endometriosis. In the secretory phase of the menstrual cycle, several estrogen-regulated genes were up-regulated in endometria of women with endometriosis. The most consistent regulation with one of the highest factors was observed for the Cyr61 gene, which codes for a secreted, cysteine-rich, heparin-binding protein that promotes cell adhesion, migration, and neovascularization. Estrogen responsiveness of endometrial Cyr61 expression was suggested by the higher expression during the proliferative phase and the reduction observed in human endometrial fragments grafted into nude mice subsequently treated with an anti-estrogen. The expression level of Cyr61 was found to be further increased in ectopic endometriotic lesions, as compared to eutopic endometria. In these lesions, an imbalance in expression of the estrogen-converting enzymes 17beta-hydroxysteroid dehydrogenase type 1 and 2 was found, which might explain the elevated Cyr61 level. However, Cyr61 expression was not altered in endometriotic lesions of women treated with a GnRH agonist. These results suggest that Cyr61 may represent a gene characteristic for endometriosis and also play an important role in the development and persistence of endometriotic lesions.